Sub-miniature pentode with two plates question

[Leka]

I have plans to test some russian sub-miniature pentodes in my wonderful Hall Amplification Lil'devil.

Originally the Lil'devil has 5902 pentodes in the output stage.
I found some military grade 6P30B-R tubes which I would like to try.

There is one thing that bothers me...
Why in these 6P30B-R pentodes there are two plates?
Can I just pair them and use as one?
Could use them with only one plate connected?
Any other reason I shouldn't try these russian tubes in my wonderful amp?

This might be trivial concern, but I am still wondering why...

[tubeswell]

http://scottbecker.net/tube/sheets/113/6/6P30B.pdf

Are we talking about this tube?

[Leka]

Close, but with -R...

I'm talking about this one:

http://oldradio.qrz.ru/tubes/russian/sh ... 0b-r.shtml

http://www.ebay.com/itm/4x-6P30B-R-Sovi ... 2ecb67876a

[tubeswell]

Where are the specs?

[TUBEDUDE]

I guess that makes it a hexode. Not many hexode amps out there I'll bet.

[Leka]

Thank you for the replies!!

There was some specs in the ebay link:

Filament voltage,V 6,3
Filament current,A 0,42-0,44
Anode voltage,V 120
Anode current,A 0,027-0,043
Anode power,W 5,5
Grid2 voltage,V 120
Steepness,mA/V 3,4-5,5
Reverse grid current,uA 0,5
Microphnic noise,mV 75
Socket type flexible

There is also a pin layout in the ebay link.

Hexode?
I think not because there is only three grids...

[TUBEDUDE]

I wonder if those values are for each plate or the pair. BTW the number of grids is irrelevant, it's just the number of elements minus the heater.

[Leka]

I wonder if those values are for each plate or the pair. BTW the number of grids is irrelevant, it's just the number of elements minus the heater.

Hexode it is then.

I guess I just have to test and find out how it works.
I'll let you know how it goes when I get there...

BTW I found a datasheet following a link from a polish forum which has both 3P30B & 3P30B-R.
They seem to be totally different beasts, different pinout also.
Unfortunately I can't read russia so I just have to guess what it's saying...
PM me if anyone got interested and I can mail it in pdf-format.

Thank you all for replies!!

[tubeswell]

...
Anode current,A 0,027-0,043
...
Steepness,mA/V 3,4-5,5

These two sets of characteristics give a little clue. I would hazard a guess that the lower end of the plate current range is with 1 plate, and the upper end is with both plates connected (and the transconductance range tells a similar story)? But its just a guess mind you.

[Leka]

...
Anode current,A 0,027-0,043
...
Steepness,mA/V 3,4-5,5

These two sets of characteristics give a little clue. I would hazard a guess that the lower end of the plate current range is with 1 plate, and the upper end is with both plates connected (and the transconductance range tells a similar story)? But its just a guess mind you.

Good guess!
Those values do vary a lot and might be as you guessed.

[shoggoth]

Hexode it is then.

Nope, it's a pentode with dual plates. I used to know what they were used for, something to do with color televisions I think.

If you were just counting elements to name a tube, a 12ax7 would be a hexode instead of a dual triode.

[TUBEDUDE]

its not every element in the bottle, just the ones that interact as a unit.

[shoggoth]

its not every element in the bottle, just the ones that interact as a unit.

By that logic a dual-plate triode is a tetrode. Gated beam discriminators are hexodes. Common-cathode dual triodes are pentodes. That's really not how tubes are classified.

Hexodes are very specific things, they've got an extra grid for modulation, and operate very similarly to heptodes.

[TUBEDUDE]

I used to align transceivers and saw many heptodes. They were used as mixer and hetrodyne stages. I never saw a hexode and didn't realize it was a real thing. I thought I just made it up.

[Leka]

Used google translator and translated some of the mystic cyrillic texts from the russian data sheet. I felt like translating the rosetta stone...

In the data sheet the two anodes where named as Small and Large.

No idea where those were needed but I guess there has been a secret plan to manufacture them like this.

I can see a lot of possibilities and hell of a lot of smoke...